It's something that still sticks with the group's father, Toby Willis, who lost his brothers and sisters in the crash.

"Life goes on, you have to just clean up, you have to go on, you have to smile, you have to go on, and I wanted to make sure people knew that we weren't just going to be sad for rest of life. We are sad, but there's joy," Toby Willis said via Facetime.

The oldest sibling in the group, 22-year-old Jessica Willis, puts a philosophical spin on it.

"Something like that in family history magnifies the fact that every second you get together, is that much more special," Jessica said.

That togetherness is obvious when you see the Willis family on stage.

"It's a lot of work. A lot of plates are spinning. We try to minimize how many crash," Toby Willis said.

The Willis Clan will be back on "America's Got Talent" in the next couple of weeks. They'll also perform at the Milwaukee Art Fest in August.